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일정 열속으로 하부면이 가열되는 수평 유체층에서 열적 불안정성 해석

The Analysis of Thermal Instability in a Horizontal Fluid Layer Heated from Below under Constant Heat Flux

HWAHAK KONGHAK, June 1988, 26(3), 330-335(6), NONE
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Abstract

초기에 정지되어 있는 수평 유체층의 하부면을 일정한 열속으로 가열할 때 자연대류의 유발시점을, 전파 이론을 근거로, 해석하였다. Deep-pool계에 대하여 기본온도분포를 적분방법에 의하여 모사하고 새로운 안정성 방정식을 유도하였다. Prandtl수가 매우 큰 경우, 임계조건들을 구하여 아래와 같은 상관식을 얻었다.
τc = 4.57Ra-1/2
'_ ^ ^
이는 기존실험치들과 Ra>104인 범위에서 잘 일치함을 보여 주었다. 또한 발생되는 자연대류는 4τc에 감지될 정도로 증폭되는 것으로 나타났다.
When an initially quiescent, horizontal fluid layer is heated uniformly from below, the critical time of the onset of natural convection is analysed by employing the propagation theory. For deep-pool systems the basic temperature profile is approximated by using the integral method and a new stability equation is generated. The critical conditions are found to have following relation:
τc = 4.57Ra-1/2 for Pr→∞
This relation agrees well with experimental data in the range of Ra>104. Also, it is seen that the initiated convection is amplified to observable magnitude at the time 4τc.

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